/* 程序B-2 输出至标准出错文件的出错处理函数*/
#include <errno.h>        /* for definition of errono */
#include <stdarg.h>       /* ANSI C header file */
#include <stdio.h>
#include <string.h>
#include "ourhdr1.h"

static void err_doit(int, const char *, va_list);
char   *pname = NULL;        /* caller can set this from argv[0] */

/* Nonfatal error related to a system call.
* Print a message and return. */

void err_ret(const char *fmt, ...)
{
    va_list    ap;
    va_start(ap, fmt);
    err_doit(1, fmt, ap);
    va_end(ap);
    return;
}

/* Fatal error related to a system call.
* Print a message and terminate */
void err_sys(const  char *fmt, ...)
{
    va_list    ap;
    va_start(ap, fmt);
    err_doit(1, fmt, ap);
    va_end(ap);
    exit(1);
}

/*Fatal error related to a system call.
* Print a message, dump core, and terminate. */
void err_dump(const char *fmt, ...)
{
    va_list    ap;
    va_start(ap, fmt);
    err_doit(1,fmt, ap);
    va_end(ap);
    abort();        /* dump core and terminate */
    exit(1);
}

/* Nonfatal error unrelated to a system calll.
* Print a message and return. */
void err_msg(const char *fmt, ...)
{
    va_list    ap;
    va_start(ap, fmt);
    err_doit(0, fmt, ap);
    va_end(ap);
    return;
}

/* Fatal error unrelated to a system call.
* Print a message and terminate. */
void err_quit(const char *fmt, ...)
{
    va_list    ap;
    va_start(ap, fmt);
    err_doit(0, fmt, ap);
    va_end(ap);
    exit(1);
}

/* Print a message and return to caller.
* Caller specifies "errnoflag". */
static void err_doit(int errnoflag, const char *fmt, va_list ap)
{
    int        errno_save;
    char       buf[MAXLINE];

    errno_save = errno;        /* value caller might want printed */
    vsprintf(buf, fmt, ap);

    if(errnoflag)
    {
        sprintf(buf+strlen(buf), ": %s", strerror(errno_save));
    }
    strcat(buf, "\n");
    fflush(stdout);          /* in case stdout and stderr are the same */
    fputs(buf, stderr);
    fflush(NULL);            /* flushes all stdio output streams */
    return;

}